Extensions of CASH+ thermodynamic solid solution model for the uptake of alkali metals and alkaline earth metals in C-S-H

The new CASH+ core sublattice solid solution model of calcium-silicate-hydrate (C-S-H) can describe calcium uptake, solubility, water content, and mean silicate chain length up to 90 °C. In this study, the has been consistently extended equilibrium uptake alkalis (Li, Na, K, Rb, Cs) alkaline earths (Mg, Sr, Ba, Ra). endmembers for each cation were defined, their properties, along with binary interaction parameters, fitted against known aqueous phase compositions. its extensions be directly used in GEMS codes or discretized exported use other geochemical speciation computer programs. agreement experimental data, indicates that earth cations occurs mainly as a competitive (interlayer) ion exchange, is favored at low C/S ratios, chains get shorter higher pH, bivalent (in order Mg2+ < Ca2+ Sr2+ Ba2+ Ra2+) preferential over monovalent (Li+ ? Na+ K+ Rb+ Cs+).